Port 3502: Avocent Install Discovery — A Data Center Appliance's First Words

Port 3502 belongs to the registered port range (1024–49151) and carries a protocol with a very specific job: helping Avocent data center appliances announce their presence during installation.

IANA's official name for it is avinstalldisc — Avocent Install Discovery — registered for both TCP and UDP.¹

What Avocent Is

Avocent (now part of Vertiv) makes the hardware that lets IT teams manage servers without being physically present. Console servers, KVM switches, out-of-band management appliances — the equipment that lets someone in another city reboot a crashed server, access its BIOS, or diagnose a network failure at 3am without driving to the data center.²

Their DSView management software sits at the center, providing a single interface for controlling all these devices across an entire organization.³

What Port 3502 Does

When an Avocent appliance first comes online, it needs to be found. Rather than requiring a technician to manually enter every device's IP address into DSView, the appliance broadcasts its presence using this port — announcing: "I exist, I'm an Avocent device, come configure me."

This is the install discovery phase. Port 3502 is the appliance's first words on the network.

Once discovered and configured, ongoing management traffic moves through other ports. Port 3502's job is essentially over — it exists for that initial handshake between a new appliance and the management software responsible for it.

What Range This Port Belongs To

Registered ports (1024–49151) are the middle tier of port space. Unlike well-known ports (0–1023) — which require administrative privileges to bind and house protocols used by everyone (HTTP, SSH, DNS) — registered ports are documented with IANA but used by specific applications and vendors.

Anyone can request a registered port assignment. Avocent did, and IANA said yes. That's the whole story of how 3502 got its name.

Is This Port a Security Concern?

Discovery protocols that broadcast appliance presence can be sensitive in environments where you'd rather not advertise what hardware exists on the network. If you're running Avocent appliances, this port should be firewalled from untrusted networks and restricted to management VLANs.

If you're not running Avocent equipment and see traffic on port 3502, that's worth investigating.

How to Check What's Listening on Port 3502

Linux / macOS:

# With ss (modern Linux)
ss -tulpn | grep 3502

# With lsof
sudo lsof -i :3502

# With netstat
netstat -tulpn | grep 3502

Windows:

netstat -ano | findstr :3502
# Then find the process:
tasklist | findstr <PID>

If something is listening on 3502 and you're not running Avocent management software, find out what it is.